Dr.diff kit is nicer, I've used the mp and dr.diff, the problem with the dr.diff kit, it's been out of stock for a long time. 6 months, a year, I don't know. Every time I emailed him i got The same story, New fabricator making them, they'll be available in a couple weeks.
The mp kit is funny, I bought a set off a guy since I couldn't get the dr diff ki, I don't remember this with my last one I used, but the front spring eye bolt is offset toward and up. I don't know if they used to sell different ones but I'm thinking these were designed for ss springs.